Television tube control system having interconnected deflecting coil and accelerating electrode



Filed Aug. 9, 1.9

O. H. SCHADE TELEVISION TUBE CONTROL SYSTEM HAVING INTERCONNECTED DEFLECTING COIL AND ACCELERAT ING ELECTROD Sheets-Sheet 1 A6/7 7 REA Hai/20mm afa/.imam m/f INVENTOR ATTORNE May 4, 1948. o. H.

DEFLECTING COIL AND Filed Aug.' 9, 1945 SCHADE 2,440,787

TELEVISION TUBE CONTROL SYSTEM HAVING INTERCONNECTED AGCELERATING- ELECTRODE 2 Sheets-Sheet 2 VERT/CAL POWER 7055 `4\ ,gam/M4 ATTORNEY Patented May 4, `19148 NITE-D STATS 'l' QFFICLE OttoH. Schade, West Caldwell, N. J., assignor to Radio Corporation of America, a corporation of Delaware ApplcationAugust. 9, 1945, Serial No. 609,889

19 Claims. 1

The present invention.relatesto` television receiving systems ofthe type in'which the scanning beam developedin a catho-de ray tube is controlled in such a mannerasto effect-the electrooptical 'reproduction of an image. The invention more particularly relates tomeans for maintaining animage raster of substantially predetermined selected size and shape: in the iace of uctuationsin the energizing voltage applied to the cathode ray tube..

The accelerating potential lon the second anode of the kinescope-commonly employedlin presentday television receivers may rise to a value ini the order of 30,000 volts, for example. While such a high potential may be derived from the relatively low-voltagey alternating-current power input to the receiver, this procedure requires components, vsuch as transformers and filters, which are notonly expensive but which, in addition, increase the size and weight of the television apparatus.

An alternative expedient'for deriving an energizing voltage for the cathode ray tube resides in the use'oi a vacuum tube oscillation generator, which may be/designedas a separatehigh-Voltag'e direct-current power supply system, or which may be the sawtooth generator forming part of the horizontal or lineI deflection circuit. In either case, such high voltage supplies have the disadvantage of relatively poor regulation, one reason for which -isset forth below.

The anode circuit of the image-reproducing cathode ray tube, or kinescope, constitutes a load the average impedance of which varies in accordance with theaverage'value'of the video signal appearing :on'the control electrode of the kinescope. In other words, if a video signal supplied from the television receiver to the control electrode of the kinescope is such. at any instant, as do cause the fluorescent screen of the cathode ray tube to be devoid of illumination, then the .kinescope constitutes a high-impedance load,

since no space current is drawn from the highvoltage supplyA by the anodes of the cathode ray tube when the scanning beam is extinguished. On the other hand, `when, the v-ideo signal from the television receiver to the control electrode of the kinescope is such as to cause the screen of the cathode ray tube to-'be brightly illuminated, then the tube is a lower-impedance load, since the space current drawn from the highvoltage supply system `by the' anodes of the tube relatively large.

Accordingly, the anode potential of the cathode ray tube would normally vary in accordance'with the video-frequency changes -in tube-impedance resulting from modulation of the scanningbeam by the vdeo signal. The power supply system of the television receiver is usuallydesigned, .how--l ever, so that thel time constant of the power supply filter condensers is suliciently large to smooth out any voltage variations which do'not extend over a period'in excess of several linescanning intervals.

In certain instances, however., asyrfor-example, in the reproduction of a landscape scene in which a substantial proportion of thevimage raster is brightly illuminated to. represent a; clear ora white sky, the time constant of the nlter condensers of the power supply is exceeded. The voltage on the accelerating electrodesY offthe cathode ray tube, under these conditions, undergoes an appreciable drop.

Such a drop inl tube accelerating voltage in conventional television systemsV results iny distortion ofV the image raster. The reason for this will be appreciated when it is considered that the angle of deection of the `cathode ray scanning beam dependsboth uponA the velocity of the beam and upon the strength of the delecting eld. Hence in lany televisionreceiver in which the deflecting eld strength is maintained substantially uniform at a predetermined level, variations in the accelerating potential on the cathode ray tube will cause corresponding variationsin the size of the image raster scanned by the beam. For example, under the conditions above set forth in which a landscape scene having a relatively large sky portion is reproduced, then the lower anode voltage caused by the increased space current during the extended period of brilliant screen illumination results in a lower scanning beam velocity. The same delecting neld intensity, acting upon the lower-velocity scanning beam, deflects'it through a larger angle, so that during this period of highlight reproduction the image raster is expanded in an objectionable manner, as exemplied in Figure 1 of the drawings.

One object or" the presentinvention, therefore, if; to provide, yin a television system employing an image-reproducing cathode ray tube, means for maintaining an image raster of substantially predetermined size and shape in the face offluctuations in the accelerating potential delivered to the electrodes of the cathode ray tube.

Another object of the present invention is to provide, in a television system employing an image-reproducing cathode ray tube, means for lcausing either or bothl the Yline and -eld dencetion potentials applied to the cathode ray tube to vary in accordance with Variations in the accelerating potentials applied to the tube, Whereby changes which would otherwise occur in the size of the image raster are automatically compensated for.

Other objects and advantages will be apparent from the following description of preferred forms of the invention and from the drawings, in which:

Fig. 1 illustrates an image raster as formed by the scanning action of the beam of a cathode ray' tube, showing the highlight area distortion existent in present conventional types of television systems; Fig. 2 illustrates a circuit in accordance with the present invention for correcting the horizontal highlight distortion only;Y

Fig. 3 illustrates the manner in which the circuit of Fig. 2 corrects the horizontal highlight distortion in the image raster shown in' Fig. 1;

Fig, 4 illustrates a circuit in accordance With the present invention for correcting both horizontal and vertical highlight distortion; f

Fig. 5 is a modication of Fig. 4 with the addif tion of a separate power supply;

Fig. 6 is a circuit diagram of an alternative arrangement showing a separate power supply f energizing both the horizontal and vertical discharge circuits; and

Figure 7 illustrates one type of high-voltage surgeftype rectier that might be utilized in the circuits of Figs. 2, 4 and 5.

Referring rst to Fig. 1, there is illustrated an image raster I0, such as formed by the scanning action of the beam of a cathode ray tube included in a conventional television receiver. As shown, both horizontal and vertical expansion occur when the accelerating potential on the anodes of the cathode ray tube is decreased as a result of a relatively large highlight area II in the reproduced image.

A television circuit for correcting only horizontal highlight distortion is shown in Fig. 2. This circuit includes e, horizontal, or line, power output tube I2 having at least an anode, a cathode, and a control electrode. Tube I2 is adapted to deliver, when voltage variations having a waveform such as indicated by the reference character I4 are applied to the control electrode thereof, cyclically varying current, a portion of each cycle of which varies in a substantially linear manner with respect to time, as shown by the current waveform I5 (a showing which is not to scale but merely to show general wave configuration and amplitude as the ordinate and timeY as the abscissa), to a pair of horizontal or line cathode ray beam deflection coils I5 through a coupling step-down transformer I8. A damper tube 20 is connected across the secondary winding of transformer I8. This tube prevents oscillations in the circuit by acting as a switch which closes at the end of the return, or snapback, portion of each cycle of the current wave I5, or, in other. Words, at the beginning of each horizontal or line deflection cycle. The switching operation of tube 2B causes a current to ow therethrough which is of such waveform as to assist the power tube I2 in causing the desired linear current ow through the deiiection coils I5. The operation of such a damper tube is set forth in applicants Patent No. 2,309,672, and hence will not herein be described in detail,

The horizontal, or line, cathode ray beam deection coils I 6 preferably form part of a yoke assembly encircling the neck of an image-reproducing cathode ray tube or kinescope 22. Included in the yoke assembly is a, pair of vertical, or eld, deection coils 24, the latter being energized in a conventional manner by sawtooth current, Which may have a Waveform such as represented by the reference character 25 (which wave merely exemplies the general form but is not to scale and which plots current as the ordinate and time as the abscissa) from a Vertical deliection generator 26 synchronized by vertical sync (also termed synchronizing) signals derived from the composite television signal appearing in the input circuit of the television receiver. This input circuit, as Well as `other portions of the complete television receiver not necessary to an understanding of the present invention, have been omitted from the drawings for the sake of clarity.

The primary winding of coupling transformer I8 is provided with a stepped-up portion 28. The voltage appearing across the stepped-up primary winding of transformer I8 is applied to a surge f type high-voltage rectifier 30, which may be of any suitable type designed to deliver a relatively smooth D.C. potential to the accelerating elecf trede 32 of kinescope 22.' The rectifying means 30 may also include means for doubling, quadrupling or otherwise increasing the Value of they Voltage output thereof, in accordance with the potential requirements of the image-reproducing tube 22. One voltage-'increasing means of the type mentioned is disclosed in applicants copend ing application Serial No. 578,678, led February 19, 1945 noW Patent No. 2,439,223 issued April 6,

As above stated, the kinescope 22 acts as a variable-impedance load. When space current is drawn by the anodes of tube 22 from the rectifier 30 due to Vextended highlight areas in the repro-- duced image, this, in effect, constitutes an inu crease in the load on the stepped-up primary winding of transformer I8. Consequently, less power is supplied to the secondary Winding 3ft of transformer I8, and the peak amplitude of the sawtooth scanning current I5 flowing through the horizontal deection coils I6 decreases.

By a proper choice of circuit constants, the decrease in scanning amplitude may be made to just compensate for the decrease in accelerating potential, so that horizontal expansion of the image raster is substantially eliminated, as shown in Fig. 3. The vertical deflection generator 2%, however, still delivers a vertical deflection current 25 of a substantially constant peak amplitude through the vertical deflection coils Ef-l. Hence, vertical expansion still is present, the correct or undistorted contours for the image raster I being indicated in Figs. 1 and 3 by the broken lines.

A circuit lfor correcting both horizontal and vertical expansion is illustrated in Fig. fl, the circuit components in this figure corresponding to those in Fig. 2 being identified by the same reference characters. A relatively high-resistance bleeder resistor 35 has one end connected to the positive terminal 38 of a source of relatively steady D.C. potential (not shown). The source of potential connected to terminal 38 may, if desired, be the same one that supplies plate voltage for the horizontal power tube I2 through a portion of the primary winding of coupling transformer IS.

The other end of bleeder resistor 36 is connected to the high-voltage rectier 3i) bymeans of a lead 40 in such a manner that the voltage supplied to the resistor 36 by the rectifier 3i) may be i5 either the full' vcltaeeffoutputf of4 the :rechner-130 as applied to the accelerating electrodez32 `of -ckinescope y22;; tor `it maynbesa.portion-f` of :thet` full voltage outputsof therrectierf. anyaevent, related uctuationsf'occurini cthe'zuoltage .output of rectier 30 v`as vaplsiliedrboth -to 4`V`tlrieflrinesccpe anode `32 andtoonetend ofz'the bleederresistor Anadjustabletap fi2 tonresistorzf3l :isconnecte'd toground through za potentiometer'lli and atrelatively high fresistor 246-. ,i-Fromthe .slider 48 of potentiometer 4d `:energy is derivedf-tcharge Ya vcondenser A5t`nrough a chargingfresistcriZ and a coupling condenser? 54.

A lvertical discharge 'tube '56 Vis `connected to ground in-parallel with Acharging-condenser i518. Discharge tube-T5S: is'n'orInall-yA `c-u-t'ol=i',--and"is rendered 'conductive to discharge condenser Awhen one of a series of positive -syncpulses, r-which may'have Va waviormsuch Las'ind'lcatedby the `reference character ESQ-is received on' the control lelectrode thereof. Thevoltage'variations:thus developed-across condenser-*'50, -whieh-wfillbe of substantially sawtooth congura-tionfare" applied to Vthe vcontrol electrode Gilrofa vvertical-power tube'62. l

Verticalpower tube @Tis yadapted'to deliver cyclically 'varying4 current havingawave-form' of substantially sawtooth configuration,"as a result of thevoltagewaveform'otsubstantially sawtooth congurationv received -on "the control electro'de thereof to the verticall or nel'd deflection coils"2'4 through'coupling transformer 64. Aswi'll novvV be shown, thepeakiamplitude ofthe cyclically' varying current owing through the vertical'deection coils .24 will change las afunction of changes in the voltage output of rectier'i.

vWhen the voltage on the acceleratingelectrode 32 of kinescope 22 decreasesgasa result ofvextended highlights. in the reproduced.image,` it' has been shown that the peak. amplitude of the .defleeting energy should likewise decrea-seinorder that the con'guration of the image. rasterseanned by the rcathode ray beam shouldremainsubstantiallyunaltered. .This .change inspeak amplitude of the deflecting current should `be approximately as thesquare root` (if-changes in tubefanodepotential, and forV small percentage changes, this value will be inthe order. of one-half.

An anode vpotentials-scanning amplitude relationship, such Aasset forthrabovais readilyobtained in the circuitof.Fig.=-4.. .,It'iwill lee-observed that the bleeder resistor-:36 actsr-asa mixeroff (l) the relatively steady D.C.fvoltage from theitervminal, and (2) .thevoltagefromthe rectifier .39, .which varies .synchronously wth-.changes-in there is one position'forltap'at which correct compensation maybe'obtained, this correct compensation being readily "d'eterminable by viewing the image reproduced on'the screen of'thekinescope 22 duringadjustment of tap 42..

A desired amount .f the voltage appearing across potentiometer *44 is' applied'to charge con- `secon'd anode 32 of Vkinescope 22. 'may,'underfcertain conditions, be similar'to th ,generator 66 of Fig. 5.

6 denserftr throughtresistor 52 tand 'couplingcondenseri. -Adjustment '..offslider- 48, byvarying the #charging potential :applied tto v condenser p50',

actsfas'a' vertical size control, as will be readily understood'by thoseskilled in 'theart. Periodic conduction 'of :discharge tubefe, as a:result fof voltage variations`-58 being-received onthencontrol electrode thereof, results in asubstantially 'sawto'oth voltage wave to be applied to thecontrol elecimode' .of verticalpower tube B2, which is thus :controlled to .deliver cyclically varying'sawtooth' current to the vertical deflection coils-24.

iBy placing the couplingcondenser in thev circuit so that it and condenser 50 are charged in -series through resistor52, and byk making it 0f re1- :atively small capacity, as, for example, .015 mf.,

it' is: possi-ble tofavoid the large D.C. transients ori thefcontrolrelectrode Bil of power tube A62 that oc- .cur when large 'coupling condensers are employed'. '.Itshouldalso' be noted that'byV this metho'd*diplacernentof coupling condenser 54, the igrid resistor =55fof power tube G2 does'not 'shunt aparla-l'lel:combination ofxcon'densers 5B and y5t, t-aszoccurs in conventional arrangements.

The circuits of both Figs. 2 and 4 include a high-voltage surge type rectier' connected to the stepped-upiprimary winding of transformer 113. This :rectier 3B will Adeliver a relatively `smooth D.-.C. output voltage which is'sufciently high in many instances to be suitable as yan accelerating potential for the second anode 32 vof kine'scope 22. However, in some cases, such as in projection type television receivers, an energizingxpotential is necessary or desirable whi-ch is greater than canbey conveniently or practically suppliedby a high-voltage rectifier of thel surge type. In? such receiving systems, a separate high voltage'D.-C. generator 63 may be added to supply voltage' for the anode"32 of kinescope 22 in series with` the high-voltage recti'iier 30, as shown in Fig. 5. In such an event, the total voltage on the kine- `scopefanode 32 will be substantially the sum' of the outputs kof the power supply devices 33 and B6,

and-variations inf the output of rectifier 3i) as a re- `sult of Vkinescope impedance changes will be applied through generator 66 to the kinescope anode A`32 ina relative proportion determined in part by the circuit constantsiof the respective power sup- 'ply devices.

vIn certain television receiver arrangements, a separate power supply for the kinescope second vanode is employed which is not associated with vthe horizontal or line deflection system, as is the surge type rectifier 3B in the circuits of Figs. 2, ,4 and5. Such a system is illustrated in Fig. 6, .in vwhich'a Yhigh-voltage D.C. generator 68 is employed'to'supply an accelerating potential for the Generator 68 Since an increase in space current drawnfrom 'thegenerator 68 by the anode o kinescope 22,

under extended high-light conditions, does not place -a greater load on the horizontal lpower transformer' i8 in the circuit of Fig. 6 to thereby resultin a decrease in horizontal peak scanning amplitude, other means must be provided Vfor bringing about this result. It will be notedthat the means for producing a decrease in vertical peak scanning amplitude by automatically decreasing 'the .chargingpotential applied to condenser 5@ isidentical in both Figs. 4 and 6, and

hence a discussion of' the vertical sizeregulating characteristics ofrthe invention will not be repeated.

To give automatic horizontal size control in connection with the separate power supply 68 of Fig. 6, a second tap is provided on bleeder resistor 36. Tap 1U is connected to ground through a potentiometer I2 and a relatively high resistance 'I4 in substantially the same manner that tap 42 is connected to ground through potentiometer 44 and resistor 46.

From the slider 16 of potentiometer 12 energy is derived to charge a condenser 18 through a charging resistor 80. It will be appreciated that adjustment of slider 16 acts to vary the charging v.potential applied to condenser 18, and hence acts as a horizontal size control.

A horizontal discharge tube 82, which is normally biased to cut-off by any suitable means, is rendered conductive when one of a series of positive sync pulses,.such as indicated by the waveform 84, is received on the control electrode 86 thereof. This results in a discharge of condenser 18, and hence a voltage Waveform of substantially sawtooth configuration is applied to the control electrode 86 of horizontal power tube I2 through coupling condenser 88.

It will now be appreciated that the position of tap 'I0 on bleeder resistor 36 determines the degree of compensation for the horizontal deection circ-uit, when changes in kinescope anode potential occur, in the same manner that the position of tap vll2 determines the degree of compensation for the Vertical deflection circuit. That is, an increase of resistor portion 35o, with .a corresponding decrease of resistor portion 36d, will increase the compensation, since a greater amount of varying voltage from generator 68 and a lesser amount of steady voltage from terminal 38 is caused to appear across potentiometer 72. Conversely, an increase in resistor portion 36d with a corresponding decrease in resistor portion 35o decreases the compensation. It has been found that once proper positions for taps d2 and 7i) have been determined, any change in these positions is usually unnecessary .as long as the constants of the remaining components of the circuit remain substantially the same.

Fig. 7 illustrates one type of high-voltage surge-type rectifier illustrated by block diagram and identified by the reference numeral 0 in Figs. 2, 4 and 5. A rectier or this general nature is illustrated and described in the applicants above-mentioned copending application, Serial No. 578,678, and hence will not be set forth in detail herein. However, this rectifier 30 may include a rectifier tube 90 the anode of which is connected to the step-up winding 28 of transformer I8 as shown. The cathode of rectier tube 90 is connected to ground through a capacitor or other energy storage device 92. During the retrace intervals of the cathode ray scanning beam of the kinescope 22, pulses of positive polarity will be applied to the anode of rectiiier tube Sil. This will render tube 90 conductive to charge capacitor 92. Since the latter is chosen to be of relatively high value, a substantially smooth D.C. potential will be developed thereon during operation of the deection circuit, and this potential is ltered Iby means of a resistor 94 so as to produce across an output capacitor 9S a potential which is sufciently stable for application to the anode 32 of kinescope 22. Although one particular type of high-voltage surge-type rectier circuit has been given in Fig, 7 as an example, it will be appreciated that any other suitable type of recti- 8 er circuit 30 may be employed in place thereof, if desired.

Having thus described my invention, I claim:

1. In a cathode ray beam deiiection circuit including a line power output tube adapted to supply cyclically varying current, a portion of each cycle of which varies in a substantially linear manner with respect to time, through a coupling transformer to a pair of cathode ray beam line deilection coils encircling the neck of a cathode ray image-reproducing tube also having a pair of field deflection coils` encircling the neck thereof and at least one accelerating electrode, and in which the voltage developed across at least one winding of said coupling transformer, as a result of the flow of said cyclically varying current therethrough, is fed to a rectifying device and then a portion of the voltage output ofsaid rectifying device applied as a D.C. energizing potential to said accelerating electrode of said cathode ray tube, whereby the voltage output of said rectifying device varies in value in accordance with the characteristics of the image reproduced by said cathode ray tube, the combination of a source of relatively stable D.C. potential, means for mixing all or a portion of said relatively stable D.C. potential with a portion of the voltage output of said rectifying device, an energy storage element, means for, applying the energy output of said mixing means to'charge said energy storage element, means for periodically discharging said energy storage element, afield power output tube having a control electrode, and means for applying the resultant uctuating charge on said energy storage element to the control electrode of said eld power output tube so that the peak value of the current output of said eld power output tube, as supplied to said pair of cathode ray beam field deflection coils, and hence the magnitude of the field deection of said cathode ray beam, will vary as a function of variations in the voltage output of said rectifying device.

2. A cathode ray Vbeam deiiecticn circuit in accordance with claim 1, further including means for varying the relative proportions of said relatively stable D.C. potential and said portion of the voltage output of said rectifying device which are present in the output of said mixing means.

3. A cathode ray beam deflection circuit in accordance with claim 1, in which said means for mixing said relatively stable D.C. potential with a portion of the voltage output of said rec tifying device includes a resistor, one end of which is connected to said source of relatively stable D.C. potential, and the other `end of which is connected to said rectifying device, said resistor being provided with an adjustable tap for deriving output energy for application to said energy storage element.

4. In a cathode ray beam deflection circuit, an image-reproducing cathode ray tube having at least one accelerating electrode and at least one beam deilection coil associated therewith, va power output tube, a transformer coupling said power output tube to said beam deflection coil, a rectier connected to one Winding of said transformer, a D.C. generator, and means for applying a portion of the output of said rectifier and the output of said D.C. generator in series to the accelerating electrode of said cathode ray tube.

5. A cathode ray beam deflection circuit in accordance with claim 4, further comprising fan-403er at least one accelerating electrodeandboth line and field Cathode ray` beam deflection coils associated therewith, a line power output tube, a transformer coupling said' line power output tube to said line cathode ray beam deflection coil, a rectier connected to one winding of said transformer, means for applying a portionvoi thev output of said rectifier to the accelerating electrode of` said cathode ray tube, means for combining relatively stable D.C. potential from a.

source with a portion of theenergy output of said rectifier so asto establish a control varia,-

tion which varies as a function of variations in the value of the output of said rectifier, means for generating a cyclically varying current for application to said elcl cathoderay beam de*-v :fiection coil, and means for applying-saidcontrol variation to regulate the peak amplitude ofthe current output of said-generatingimeans.

7. A cathode -ray beam deection circuit in accordance with claim 6, in which said means ior generating a cyclicallyV varying current for application to said eld cathode ray` beam deiiection coil includes. a condenser, means forI applying said control variation to charge saidcondenser, and meansl for periodically discharging said condenser.

3. A cathode ray beam deilection circuit in accordace with claim 6, further-including means for varying the relative amounts of said rela'- tively stabley D.C potential and' of the energy output of said rectifier whichitogether comprise4 said control variation.

9. A cathode ray beam deection Lcircuit in accordance with claim 6,'in which said means for generating a cyclically varying current forapplicatien to said eld cathode ray beam de flection coil includes va coupling condenser, a

charging resistor, a charging condenser, means for applying said control variation to chargesaidcoupling condenser andsaid charging condenser in series through said charging resistor,

and means for periodically. discharging said charging condenserr so as to develop recurrent voltage variations thereacross.

l0. In a cathode ray beam deflection circuit, an image-reproducing -cathode ray tube having at least one accelerating electrode and with `bothI line and iield cathode ray beam deflectiony coils associated therewith, a D.C. generator, means for applying a portion of the energy outputof said D.C. generator to the accelerating electrode of said cathode ray tube, a line power output tube having a control electrode andi adapted to deliver cyclically varying currentto said line cathode ray beam deilection coil, means, including a condenser, for generating a cyclically varying voltage for application totheY control electrode of-said line power outputv tube, means fory combining relativelystable- D.C. voltage from a source with a portion ofI 1G thel energy output. of said D.C. generator so as to. establish4 a control potential which varies asa function o f variations inthe value of the energy output ofV said D.C; generator, means for` applying said control potential to charge said condenser, whereby` the peak amplitude of the said'cyclically. varying voltage applied to the control'electrode of said line power output tube Willvary as a function of, variations in said control potential, aiield'power output tubehaving .a control electrode and adapted Ato deliver'cyclically varying current to said field cathode ray beam. deflection coil, means, including a second condenser, .for generating a cyclically var-ying voltage for application to the control'elec-trode of said i'leld power output tube, means for establishing a second control potential from said relatively stable D.C voltage combined with.

a portion of the energy output of saidDfC..

generator, and means for 'applying SaidseCOndcontrol potential to charge said second condenser, whereby the peak amplitude of the lcycli-v cally varying volta-ge applied to the control electrode of'said fieldv power output tube will vary as afunction of variations in the value or-V thev energy outputof said D.C. generator.

11. In a cathode ray beamdeflection circuit, an image-reproducing cathode ray tube having atleast one accelerating electrode` andbothline and field cathode ray beam deection coils as,- sociated` therewith, a D.`C. generator,= means for,l applying, a portion of the energy output of said D.C. generator to the accelerating electrode of said: cathode ray tube, means for apply-ingv another portion of thel energy output of said D;-C. generator tov one end of aV resistorelement,

means. for applying a relatively stable` D.C.

potential to the other end of said resistor ele.- ment, a line power output tube adapted to supply cyclically varying current to said line cathode ray beam deilection coils, a discharge circuit,V inf cluding a condenser, for said line power output: tube, means connecting the condenser of saidv discharge circuit to a point on saidresistor-element, aneld power output tube adapted to supply cyclically varying current to said field cathodel ray beamdeflection coils, a discharge circuit, including a second condenser, for said eld power output tube, and means for connecting said second condenser to a point onsaid resistor.

element.

12. In a cathode raybeam deflection circuit,

including an image-reproducing cathoderay tube having at. least one accelerating electrode and, at least one coil yfor deflecting the cathode ray,

ray beam of said cathode ray tube as a resultl of` highlight area-s in the reproduced image, said means lincluding means for rectifying the energy developed across at least one winding ofv said coupling transformer, and means for applying said rectified energy to the accelerating electrode of'said cathode ray tube in series withthe energyl output `of said D.C. generator.

13, In a cathode ray beam deflection circuit including an image-reproducing cathode ray 11 tube having at least one accelerating electrode and both line and field deflection coils for defiecting the cathode ray scanning beam of said cathode ray tube when cyclically varying current is passed therethrough, said cathode ray beam deflection circuit also including means for generating a rst cyclically varying current and for supplying said current to said line cathode ray beam deflection coil through a coupling transformer, the energizing potential for the accelerating electrode of said ycathode ray tube being obtained by rectifying the energy developed across at least one winding of said coupling transformer and applying a portion of said rectii'ied energy to the accelerating electrode of said cathode ray tube, means for compensating for changes in the configuration of the image raster scanned by the cathode ray beam of said cathode ray tube as a result of highlight areas in the reproduced image, said means including means for mixing a portion of said rectied energy with a relatively stable D.C. potential, means for generating a further cyclically varying current and for supplying said further cyclically varying current to said eld cathode ray beam deiiectionV coil, and means for applying the output of said mixing means to control the ygeneration of said further cyclically varying current.

14. In a television system in which the substantially predetermined configuration of the image raster scanned by the .beam of an imagereproducing cathode ray tube is subject to vertical distortion as a result of changes in the energizing potential applied to said cathode ray tube caused by extended highlight areas in the reproduced image, said energizing potential being derived from the cyclic reactive energy developed as a result of the periodic horizontal deflection of the cathode ray scanning beam, the novelty of means for correcting said vertical distortion, said correcting means including means for deriving energy which changes as a function of changes in the value of the energizing potential applied to said cathode ray tube, and means for applying the energy so derived to regulate the vertical scanning action of said cathode ray scanning beam.

15. In a cathode ray beam deflection circuit, an image-reproducing -cathode ray tube having at least one accelerating electrode and both lineand i'leld cathode ray beam deection -coils associated therewith, a circuit wherein line deiiecting voltages for defiecting the cathode ray beam at line-scanning frequency are developed, said line deiiecting voltage developing circuit being coupled to said line cathode ray beam deflection coil, a rectifier connected to rectify at least a portion of the voltage developed across said line cathode ray beam deection coil, a circuit ttor applying a portion of the output of said rectier to the accelerating electrode of said cathode ray tube, a further circuit for combining relatively stable D.C. potential from a source with a p0rtion of the energy output of said rectifier so asy to establish a control variation which varies as a function of variations in the value of the output of said rectifier, a still further circuit wherein field deecting voltages for delecting the cathode ray beam at iield-scanning frequency are developed, said eld defiecting voltage developing circuit being coupled to said iield cathode ray beam deiiection coil,v and a connection for applying said control variation to said field deecting Voltage developing circuit so as 12 to regulate the peak amplitude of said field dee fleeting voltage."

16. In a cathode ray beam deflection circuit including an image-reproducing cathode ray tube having at least 'one accelerating electrode and both line and field deflection coils for deflecting the cathode ray scanning vbeam developed within said cathode ray tube relating to a selected target area when cyclically varying current is passed therethrough, a first sawtooth wave generating circuit for developing a first cyclically varying current at substantially linescanning frequency, a coupling transformer connection for supplying said current to said line cathode ray beam deflection coil, a rectier connected across at least Vone winding of said coupling transformer to produce from the pulse energy in the transformer a D.C. energizing potential for the acceleratingelectrode'of said cathode ray tube, a second' sawtooth wave generating circuit for developing a cyclically varying current at substantially field-scanning frequency, a circuit connection for supplying said further cyclically varying current to said eld cathode ray beam deilection coil, a circuit for mixing a portion of said rectied energy with a relatively stable D.C. potential in such proportions .as to compensate for changes in the configuration of the image raster scanned by the cathode ray beam of said cathode ray tube as a result of continued periods when the beam current exceeds a predetermined average value,

- and a further circuit connection for applying the output of said mixing circuit to the second sawtooth wave generating circuit so as to control the development of said further cyclically Varying current.

17. In a television system in which the substantially predetermined configuration of the image raster traced on a cathode ray device by a cathode ray .beam moving in relatively rapid line traces and in relative slow mutually perpendicular eld traces, where distortion in the direction of relatively slow beam motion comes .about as a result of changes lin the energizing potential applied to said cathode ray tube during periods when relatively long continued high beam currents are drawn by the tube during the scanning, and in a system wherein the said energizing potential is derived from the cyclic reactive Y energy developed as a result of the periodic line deection of the cathode ray scanning beam, the combination of a circuit for deriving energy which changes as a function of changes in the value of the energizing potential applied to said cathode ray tube, and a connection from the reactive energy developing circuit to apply a portion of the energy thus derived to modify the iield scanning action of said cathode ray scanning beam in a manner to compensate for raster distortion in the eld scanning direction.

18. Ina television system in which the substantially predetermined configuration of the image raster traced on a cathode ray device by a cathode ray beam moving in relatively rapid line traces and in relatively slow mutually perpendicular eld traces, where distortion in the direction of relatively slow beam motion comes about as a result of changes in the energizing lpotential applied to accelerate the developed cathode ray beam, in the direction of the target area during periods when relatively long continued high beam currents are drawn bythe tube during the scanning, and in a system wherein said energizing potential is derived from the cyclic reactive energy developed as a result of the periodic line deflection of the cathode ray scanning beam, the method of correcting distortion of the raster in the field scanning direction which comprises the steps of deriving energy which is substantially proportional in magnitude to a selected function of the changes in the value of the derived energizing potential applied to accelerate the developed cathode ray beam in the direction of the impact target area, and applying the energy thus derived to so regulate the field scanning pattern of said cathode ray scanning beam as to compensate for said introduced pattern distortion.

19. In a cathode ray beam deiiection circuit including an image-reproducing cathode ray tube having at least one accelerating electrode and both line and field deflection coils for deecting the cathode ray scanning beam developed Within said cathode ray tube relative to a selected target area when cyclically varying current is passed therethrough, and in which the normally substantially smooth D.C. potential supplied to the said accelerating electrode of said cathode ray tube is derived from the cyclic reactive energy developed as a result of the cyclically varying current .passing through said line cathode ray beam deflection coils, the method of compensating for changes in the conguration of the image raster traced on the target area by the cathode ray beam as a result of variations in the value of said normally substantially smooth D.C, potential caused by continued high beam current of the scanning cathode ray beam which comprises developing a rst cyclically varying current, supplying said rst cyclically varying current to deflect the said cathode ray beam in its line traces, developing -a second -cyclically varying current, supplying said second cyclically varying current to deect the said cathode ray beam in its field traces, combining a part of the said varying D.C. potential derived from the cyclic reactive energy with a stable D.C. potential in such proportions as to correct for distortion in image raster configuration Which results from continued high beam current conditions, and applying said combined potentials to control the development of said second cyclically varying current.

OTTO H. SCHADE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,188,647 Busse Jan. 30, 1940 

